Question

how can I use function name passed as argument.

example:

showError('container', 'id', '- message', 'show');
showError('container', 'id', '', 'hide');


function showError(container, id, msg, action)
{    
    if(action == 'show') {  
        $('#' + container).show();       
        $('#' + id).html(msg).show();
    }
    else {  
        $('#' + container).hide();       
        $('#' + id).html(msg).hide();
    }

}

Answer 1

In the general case, the bracket notation is good. In your case, use toggle:

function showError(container, id, msg, action)
{    
        $('#' + container).toggle(action === 'show');       
        $('#' + id).html(msg).toggle(action === 'show');
}

or even (as Bergi suggests):

function showError(container, id, msg)
{    
        $('#' + container).toggle(!!msg);       
        $('#' + id).html(msg);
}

(It uses my own invention, the double-bang !!, which converts truthy or falsy values to their Boolean equivalents.)